The three drugs studied include Humira, Enbrel and Remicade, all from a relatively new class of medications called TNF-alpha inhibitors. The Swedish research team note that early intervention with these drugs is now recommend to slow progression of rheumatoid arthritis, which causes painful inflammation in the joints.

However, "understanding risk versus benefits of treatment with the most commonly prescribed biologics is important for physicians and patients in managing rheumatoid arthritis," study lead author Dr. Julia Fridman Simard, of the Clinical Epidemiology Unit at the Karolinska Institute, in Stockholm, said in a journal news release.

One expert in the United States agreed.

Dr. Steven Carsons is chief of the division of rheumatology, allergy and immunology at Winthrop-University Hospital in Mineola, N.Y. He said that while there's been much "enthusiasm" for this class of drugs, it has "been tempered by concern for potentially serious side effects including infection and cancer. To date, there is debate among rheumatologists concerning the relative safety of individual TNF-alpha inhibitors."

In the new study, Simard's team compiled information on patients with rheumatoid arthritis who began treatment between 2003 and 2008. Of these patients, more than 1,600 started taking adalimumab (Humira), almost 2,700 were prescribed etanercept (Enbrel), and more than 2,000 began treatment with infliximab (Remicade).

During the five-year study, 211 of the patients died. However, the researchers found no difference in death rates among the three drugs.

According to Carsons, "it is reassuring that these authors found a mortality rate among TNF-alpha inhibitor-treated rheumatoid arthritis patients that was low ... similar to that found in prior clinical trials, and did not differ among the three TNF-alpha inhibitors studied. This information should assist rheumatologists and their patients when choosing among newer agents available to treat [the disease]."

However, the study authors stressed that more research may be needed to clarify risks for particular patients.

"While we found no statistically significant difference in mortality rates across the three biologic therapies, further studies are needed to determine if this is true across certain subsets of patients with rheumatoid arthritis," Simard concluded.